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pcds (version 0.1.4)

TSDomPEBin1D: A test of segregation/association based on domination number of Proportional Edge Proximity Catch Digraph (PE-PCD) for 1D data - Binomial Approximation

Description

An object of class "htest" (i.e., hypothesis test) function which performs a hypothesis test of complete spatial randomness (CSR) or uniformity of Xp points within the subintervals based on Yp points (both residing in the interval \((a,b)\)).

If Yp=NULL the support interval \((a,b)\) is partitioned as Yp=(b-a)*(0:nint)/nint where nint=round(sqrt(nx),0) and nx is number of Xp points, and the test is for testing the uniformity of Xp points in the interval \((a,b)\). If Yp points are given, the test is for testing the spatial interaction between Xp and Yp points.

In either case, the null hypothesis is uniformity of Xp points on \((a,b)\). Yp determines the end points of the intervals (i.e., partition the real line via intervalization) where end points are the order statistics of Yp points.

The alternatives are segregation (where Xp points cluster away from Yp points i.e., cluster around the centers of the subintervals) and association (where Xp points cluster around Yp points). The test is based on the (asymptotic) binomial distribution of the domination number of PE-PCD for uniform 1D data in the subintervals based on Yp points.

The function yields the test statistic, \(p\)-value for the corresponding alternative, the confidence interval, estimate and null value for the parameter of interest (which is \(Pr(\)domination number\(=2)\)), and method and name of the data set used.

Under the null hypothesis of uniformity of Xp points in the interval based on Yp points, probability of success (i.e., \(Pr(\)domination number\(=2)\)) equals to its expected value under the uniform distribution) and alternative could be two-sided, or left-sided (i.e., data is accumulated around the Yp points, or association) or right-sided (i.e., data is accumulated around the centers of the subintervals, or segregation).

PE proximity region is constructed with the expansion parameter \(r \ge 1\) and centrality parameter c which yields \(M\)-vertex regions. More precisely \(M=a+c(b-a)\) for the centrality parameter c and for a given \(c \in (0,1)\), the expansion parameter r is taken to be \(1/\max(c,1-c)\) which yields non-degenerate asymptotic distribution of the domination number.

The test statistic is based on the binomial distribution, when domination number is scaled to have value 0 and 1 in the one interval case (i.e., Domination Number minus 1 for the one interval case). That is, the test statistic is based on the domination number for Xp points inside the interval based on Yp points for the PE-PCD . For this approach to work, Xp must be large for each subinterval, but 5 or more per subinterval seems to work fine in practice. Probability of success is chosen in the following way for various parameter choices.

asy.bin is a logical argument for the use of asymptotic probability of success for the binomial distribution, default is asy.bin=FALSE. It is an option only when Yp is not provided. When Yp is provided or when Yp is not provided but asy.bin=TRUE, asymptotic probability of success for the binomial distribution is used. When Yp is not provided and asy.bin=FALSE, the finite sample asymptotic probability of success for the binomial distribution is used with number of trials equals to expected number of Xp points per subinterval.

Usage

TSDomPEBin1D(
  Xp,
  Yp = NULL,
  int,
  c = 0.5,
  asy.bin = FALSE,
  end.int.cor = FALSE,
  alternative = c("two.sided", "less", "greater"),
  conf.level = 0.95
)

Value

A list with the elements

statistic

Test statistic

p.value

The \(p\)-value for the hypothesis test for the corresponding alternative

conf.int

Confidence interval for \(Pr(\)domination number\(=2)\) at the given level conf.level and depends on the type of alternative.

estimate

A vector with two entries: first is is the estimate of the parameter, i.e., \(Pr(\)domination number\(=2)\) and second is the domination number

null.value

Hypothesized value for the parameter, i.e., the null value for \(Pr(\)domination number\(=2)\)

alternative

Type of the alternative hypothesis in the test, one of "two.sided", "less", "greater"

method

Description of the hypothesis test

data.name

Name of the data set

Arguments

Xp

A set of 1D points which constitute the vertices of the PE-PCD.

Yp

A set of 1D points which constitute the end points of the subintervals, default is NULL. When Yp=NULL, the support interval \((a,b)\) is partitioned as Yp=(b-a)*(0:nint)/nint where nint=round(sqrt(nx),0) and nx is the number of Xp points.

int

Support interval \((a,b)\) with \(a<b\). uniformity of Xp points in this interval is tested.

c

A positive real number which serves as the centrality parameter in PE proximity region; must be in \((0,1)\) (default c=.5).

asy.bin

A logical argument for the use of asymptotic probability of success for the binomial distribution, default asy.bin=FALSE. It is an option only when Yp is not provided. When Yp is provided or when Yp is not provided but asy.bin=TRUE, asymptotic probability of success for the binomial distribution is used. When Yp is not provided and asy.bin=FALSE, the finite sample asymptotic probability of success for the binomial distribution is used with number of trials equals to expected number of Xp points per subinterval.

end.int.cor

A logical argument for end interval correction, default is FALSE, recommended when both Xp and Yp have the same interval support.

alternative

Type of the alternative hypothesis in the test, one of "two.sided", "less", "greater".

conf.level

Level of the confidence interval, default is 0.95, for the probability of success (i.e., \(Pr(\)domination number\(=2)\) for PE-PCD whose vertices are the 1D data set Xp.

Author

Elvan Ceyhan

References

See Also

TSDomPEBin and PEdom1D

Examples

Run this code
a<-0; b<-10; int<-c(a,b)
c<-.4

r<-1/max(c,1-c)

#nx is number of X points (target) and ny is number of Y points (nontarget)
nx<-20; ny<-4;  #try also nx<-40; ny<-10 or nx<-1000; ny<-10;

set.seed(1)
Xp<-runif(nx,a,b)
Yp<-runif(ny,a,b)
PEdom1D(Xp,Yp,r,c)

plotIntervals(Xp,Yp,xlab="",ylab="")
plotPEregsMI(Xp,Yp,r,c)

TSDomPEBin1D(Xp,Yp,int,c,alt="t")
TSDomPEBin1D(Xp,int=int,c=c,alt="t")

TSDomPEBin1D(Xp,Yp,int,c,alt="l")
TSDomPEBin1D(Xp,Yp,int,c,alt="g")
TSDomPEBin1D(Xp,Yp,int,c,end=TRUE)
TSDomPEBin1D(Xp,Yp,int,c=.25)

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